CP violation in $D^0\to (K^{-}{K}^{+},{\pi }^{-}{\pi }^{+})$ from diquarks

Abstract

The explanation of the large CP asymmetries in $D^0\to ({\pi }^{+}{\pi }^{-},K^{+}{K}^{-})$ decays observed by the LHCb collaboration is likely to call for new physics beyond the CKM paradigm. We explore new contributions caused by the color-sextet scalar diquark, and demonstrate that the diquark with the mass of order 1 TeV and nominal couplings with quarks can generate the CP asymmetries at the percent level. Using the experimental data on branching ratios and CP asymmetries of $D^0\to ({\pi }^{+}{\pi }^{-},K^{+}{K}^{-})$, we derive the constraints on the diquark mass and couplings, which can be further examined on hadron colliders in the dijet final states.

Comments: 9 pages, 3 figures, reference added